An outbreak of Acinetobacter calcoaceticus infection in a neonatal care unit

Outbreaks of healthcare-associated infections linked to water-containing hospital equipment: a literature review

BACKGROUND

Healthcare-associated infections (HAIs) are a significant cause of morbidity and mortality in hospitalized patients. Water in the environment can be a source of infection linked to outbreaks and environmental transmission in hospitals. Water safety in hospitals remains a challenge. This article has summarized available scientific literature to obtain an overview of outbreaks linked to water-containing hospital equipment and strategies to prevent such outbreaks.

METHODS

We made a list of water-containing hospital equipment and devices in which water is being used in a semi-closed circuit. A literature search was performed in PubMed with a search strategy containing the names of these medical devices and one or more of the following words: outbreak, environmental contamination, transmission, infection. For each medical device, we summarized the following information: the function of the medical device, causes of contamination, the described outbreaks and possible prevention strategies.

RESULTS

The following water-containing medical equipment  or devices were identified: heater-cooler units, hemodialysis equipment, neonatal incubators, dental unit waterlines, fluid warmers, nebulizers, water traps, water baths, blanketrol, scalp cooling, and thermic stimulators. Of the latter three, no literature could be found. Of all other devices, one or more outbreaks associated with these devices were reported in the literature.

CONCLUSIONS

The water reservoirs in water-containing medical devices can be a source of microbial growth and transmissions to patients, despite the semi-closed water circuit. Proper handling and proper cleaning and disinfection can help to reduce the microbial burden and, consequently, transmission to patients. However, these devices are often difficult to clean and disinfect because they cannot be adequately opened or disassembled, and the manufacturer's cleaning guidelines are often not feasible to execute. The development of equipment without water or fluid containers should be stimulated. Precise cleaning and disinfection guidelines and instructions are essential for instructing healthcare workers and hospital cleaning staff to prevent potential transmission to patients.

The Role of Patient Care Items as a Fomite in Healthcare-Associated Outbreaks and Infection Prevention

Patient-care items can serve as a source or reservoir for healthcare-associated pathogens in hospitals. We reviewed healthcare- associated outbreaks from medical equipment and provide infection prevention recommendations. Multiple healthcare-associated outbreaks via a contaminated patient-care item were identified, including infections with multidrug-resistant organisms. The type of patient care items implicated as a fomite causing healthcare-associated infections (HAIs) has changed over time. Patient populations at risk were most commonly critically ill patients in adult and neonatal intensive care units. Most fomite related healthcare-associated outbreaks were due to inappropriate disinfection practices. Repeated healthcare-associated outbreaks via medical equipment highlight the need for infectious disease professionals to understand that fomites/medical devices may be a source of HAIs. The introduction of new and more complex medical devices will likely increase the risk that such devices serve as a source of HAIs. Assuring appropriate cleaning and disinfection or sterilization of medical equipment is necessary to prevent future fomite-associated outbreaks.

Response to Bile Salts in Clinical Strains of Acinetobacter baumannii Lacking the AdeABC Efflux Pump: Virulence Associated with Quorum Sensing

Introduction:Acinetobacter baumannii is an opportunistic nosocomial pathogen associated with multiple infections. This pathogen usually colonizes (first stage of microbial infection) host tissues that are in contact with the external environment. As one of the sites of entry in human hosts is the gastrointestinal tract, the pathogen must be capable of tolerating bile salts. However, studies analyzing the molecular characteristics involved in the response to bile salts in clinical strains of A. baumannii are scarce. Material and Methods: Microbiological and transcriptional studies (arrays and RT-PCR) in the response to bile salts were carried out in isogenic (A. baumanni ΔadeB ATCC 17978 and A. baumannii ΔadeL ATCC 17978) and clinical strains from clone ST79/PFGE-HUI-1 which is characterized by lacking the AdeABC efflux pump and by overexpression the AdeFGH efflux pump. Results and Discussion: In presence of bile salts, in addition to the glutamate/aspartate transporter were found overexpressed in A. baumannii ΔadeB ATCC 17978, the virulence factors (surface motility, biofilm, and Type VI Secretion System) which are associated with activation of the Quorum Sensing system. Overexpression of these factors was confirmed in clinical strains of clone ST79/PFGE-HUI-1. Conclusions: This the first study about the adaptive response to bile salts investigating the molecular and microbiological characteristics in response to bile salts of an isogenic model of A. baumannii ATCC 17978 and clinical isolates of A. baumannii (clinical strains of ST79/PFGE-HUI-1) lacking the main RND efflux pump (AdeABC). Clinical isolates of A. baumannii lacking the AdeABC efflux pump (clone ST79/PFGE-HUI-1) displayed a new clinical profile (increased invasiveness) possibly associated with the response to stress conditions (such as the presence of bile salts).

Systematic review of invasive Acinetobacter infections in children

INTRODUCTION

Clinicians are generally familiar with Acinetobacter as an etiological agent for serious nosocomial infections in intensive care units. However, there are no previous reviews of the full spectrum of invasive infections in children.

METHODS

A systematic review of the literature was completed up to December 2008 for reports of invasive Acinetobacter infections in children.

RESULTS

There were 101 studies that met the inclusion criteria including 18 possible outbreaks, 33 case series and 49 case reports. Suspected outbreaks were concentrated in neonatal intensive care units (16 of 18 outbreaks) and involved bacteremia or meningitis. Proof of isolate clonality or identification of the source of the outbreak was seldom established. Case series were primarily of children younger than five years of age presenting with bacteremia (sometimes multiresistant), meningitis, endocarditis or endophthalmitis, with many community-acquired infections being reported from India. Case reports consisted of unique presentations of disease or the use of novel therapies. Attributable mortality in the outbreaks and case series combined was 68 of 469 (14.5%).

DISCUSSION

Invasive Acinetobacter infections in children usually manifest as bacteremia, meningitis or both, but can result in a wide variety of clinical presentations. Outbreaks are primarily a problem in newborns with underlying medical conditions. Most reports of community-acquired infections are from tropical countries. The study of the mechanism of colonization and infection of children in intensive care units and of neonates in tropical countries may provide some insight into prevention of invasive infections.

Epidemiology of and risk factors for Acinetobacter species bloodstream infection in children

BACKGROUND

Acinetobacter species has emerged as an important cause of healthcare-associated bloodstream infections (BSI) in adults. Little is known about development of Acinetobacter spp. BSI in children.

METHODS

A retrospective case-control study was conducted at a tertiary care children's hospital between January 1, 2000 and July 31, 2005. All patients with Acinetobacter spp. BSI (N = 92) were compared with a random sample of patients with non-Acinetobacter spp. Gram-negative rod BSI (N = 156).

RESULTS

Acinetobacter spp. were isolated from blood cultures in 7% of the 1269 patients with Gram-negative rod BSI during the study period. The median age of patients with Acinetobacter spp. BSI was 5.4 years (interquartile range 1.8-13.2 years) and 57% were male. Antibiotic susceptibility patterns of Acinetobacter spp. isolates varied by class: 47% were nonsusceptible to cefotaxime; 3% were nonsusceptible to imipenem; 3% were nonsusceptible to ciprofloxacin. On multivariable analysis, patients with Acinetobacter spp. BSI were significantly more likely to develop their infection in the home setting [adjusted odds ratio (OR) = 3.58; 95% confidence interval (CI): 1.89-6.79], to be male (adjusted OR = 2.25; 95% CI: 1.24-4.08), to have a solid malignancy (adjusted OR = 4.23; 95% CI: 2.00-8.95), and to have renal failure (adjusted OR = 5.16; 95% CI: 1.07-24.96).

CONCLUSIONS

Acinetobacter spp. are an underreported cause of endemic BSI in children. Patients with Acinetobacter spp. BSI are more likely to develop their infection in the home setting compared with patients with BSI caused by other Gram-negative rods.

Control of an outbreak of pandrug-resistant Acinetobacter baumannii colonization and infection in a neonatal intensive care unit

OBJECTIVE

To investigate the potential reservoir and mode of transmission of pandrug-resistant (PDR) Acinetobacter baumannii in a 7-day-old neonate who developed PDR A. baumannii bacteremia that was presumed to be the iceberg of a potential outbreak.

DESIGN

Outbreak investigation based on a program of prospective hospital-wide surveillance for nosocomial infection.

SETTING

A 24-bed neonatal intensive care unit in a 2,200-bed major teaching hospital in Taiwan that provides care for critically ill neonates born in this hospital and those transferred from other hospitals.

INTERVENTIONS

Samples from 33 healthcare workers' hands and 40 samples from the environment were cultured. Surveillance cultures of anal swab specimens and sputum samples were performed for neonates on admission to the neonatal intensive care unit and every 2 weeks until discharge. The PDR A. baumannii isolates, defined as isolates resistant to all currently available systemic antimicrobials except polymyxin B, were analyzed by pulsed-field gel electrophoresis. Control measures consisted of implementing contact isolation, reinforcing hand hygiene adherence, cohorting of nurses, and environmental cleaning.

RESULTS

One culture of an environmental sample and no cultures of samples from healthcare workers' hands grew PDR A. baumannii. The positive culture result involved a sample obtained from a ventilation tube used by the index patient. During the following 2 months, active surveillance identified PDR A. baumannii in 8 additional neonates, and isolates from 7 had the same electrokaryotype. Of the 9 neonates colonized or infected with PDR A. baumannii, 1 died from an unrelated condition. Reinforcement of infection control measures resulted in 100% adherence to proper hand hygiene protocol. The outbreak was stopped without compromising patient care.

CONCLUSIONS

In the absence of environmental contamination, transient hand carriage by personnel who cared for neonates colonized or infected with PDR A. baumannii was suspected to be the mode of transmission. Vigilance, prompt intervention and strict adherence to hand hygiene protocol were the key factors that led to the successful control of this outbreak. Active surveillance appears to be an effective measure to identify potential transmitters and reservoirs of PDR A. baumannii.

Outbreak of Acinetobacter baumannii bacteremia in a neonatal intensive care unit: clinical implications and genotyping analysis

BACKGROUND

Outbreaks of sepsis associated with have been rarely reported in neonatal intensive care units (NICUs). We describe such an outbreak in a NICU, and the results of molecular epidemiologic investigations are presented.

MATERIALS AND METHODS

Between August and September 2000, 6 premature infants hospitalized in a pediatric NICU developed sepsis. Three additional cases had infections during November and December. For an environmental culture survey, 94 environmental specimens and hand washings of all 43 health care workers involved in this unit were examined for the presence of this organism. Two genotyping methods, pulsed field gel electrophoresis of genomic DNA digested with I and infrequent restriction site polymerase chain reaction, were used to analyze the 9 bacteremic isolates and any isolates obtained from the environmental survey and the hand washings. Another 3 bacteremic isolates of collected in the same NICU in 1999 were incorporated as controls.

RESULTS

The 9 infants were premature and had birth weights of <1,500 g. Before onset of sepsis 9 infants had received total parenteral nutrition, and 8 infants had had central venous catheters and received intrafat emulsion. Five (5.3%) environmental specimens and 10 (23.3%) hand washing specimens were positive for the organism. Except for the strain from Case 9, the results of both genotyping methods were concordant; 11 patterns were identified by infrequent restriction site polymerase chain reaction and 10 patterns by pulsed field gel electrophoresis. One major genotype was demonstrated in the first 6 bacteremic isolates as well as 3 hand washing isolates. The genotypes of the other 3 bacteremic isolates, the 3 control strains, the 5 environmental isolates and 7 other hand washing isolates were distinct from the genotype of outbreak strains.

CONCLUSION

An outbreak of bacteremia in a NICU was clearly demonstrated by the molecular epidemiologic investigation and was possibly transmitted via the hands of health care workers.

Carriage of gram-negative bacilli in young Brazilian children with community-acquired pneumonia

BACKGROUND

Gram-negative bacilli are not infrequently encountered as etiologic organisms of pneumonia in children in warm-climate countries.

OBJECTIVES

To investigate the nasopharyngeal carriage rate and antimicrobial susceptibility patterns of gram-negative bacilli colonizing children with community-acquired pneumonia in Fortaleza, Brazil.

METHODS

A single nasopharyngeal specimen was collected from children 2 months to 5 years of age presenting at one of the three children's hospitals in Fortaleza and fulfilling the World Health Organization criteria for pneumonia. Randomly recruited healthy children from public daycare centers and immunization clinics served as controls.

RESULTS

The study included 912 children, 482 (53%) with pneumonia and 430 (47%) controls. Aerobic gram-negative bacilli were seen in 79 (16%) of the 482 children with pneumonia and 51 (12%) of the 430 healthy controls. Nonfermentative gram-negative bacilli were seen in 85 (18%) of children with pneumonia and 54 (13%) of healthy controls. Neither gender, nutritional status, season, previous hospital admission nor antibiotic use was associated with carriage with gram-negative bacilli. However, pneumonia was associated with increased carriage, whereas concomitant colonization with Streptococcus pneumoniae or Haemophilus influenzae was associated with decreased carriage with gram-negative bacilli. Only 36% of all Escherichia species and 76% of all Klebsiella isolates were susceptible to cotrimoxazole; 90% of all Acinetobacter species were susceptible to gentamicin.

CONCLUSION

Nasopharyngeal carriage with gram-negative bacilli, in particular with Acinetobacter species, is common and associated with a clinical diagnosis of community-acquired pneumonia in children in Fortaleza, Brazil.

Outbreak of Acinetobacter spp. bloodstream infections in a nursery associated with contaminated aerosols and air conditioners

BACKGROUND

Acinetobacter spp. are multidrug-resistant bacteria that grow well in water and cause infections with unexplained, increased summer prevalence. In August, 1996, eight infants acquired Acinetobacter spp. bloodstream infection (A-BSI) while in a nursery in the Bahamas; three infants died and an investigation was initiated.

METHODS

A case patient was defined as any newborn in the nursery during August 6 to 13, 1996, with A-BSI. To identify risk factors for A-BSI we conducted a retrospective cohort study and performed environmental cultures and air sampling using settle plates. The genetic relatedness of environmental isolates was assessed by pulsed field gel electrophoresis.

RESULTS

Of 33 patients in the nursery 8 (24%) met the case definition. Patients with peripheral iv catheters were more likely to develop A-BSI (8 of 21 vs. O of 10, P < 0.05). Multivariate analysis among patients with iv catheters indicated that only exposure to one nurse was an independent risk factor for developing A-BSI (P < 0.005). Nursery settle plates were more likely to grow Acinetobacter spp. than were settle plates from other hospital areas (8 of 9 vs. 0 of 5, P < 0.005); cultures from nursery air conditioners also grew Acinetobacter spp. Environmental isolates were genetically diverse. After installation of a new air conditioner in May, 1995, A-BSIs occurred more frequently during months of increased absolute humidity or environmental dew point.

CONCLUSIONS

Acinetobacter spp. may cause nosocomial BSI and death among infants during periods of polyclonal airborne dissemination; breaks in aseptic technique during i.v. medication administration may facilitate transmission from the environment to the patient. Environmental conditions that increase air conditioner condensate may predispose to airborne dissemination via contaminated aerosols and increase the risk of nosocomial A-BSI.

Eradication of Acinetobacter baumannii by photosensitized agents in vitro

The photodynamic effects of photosensitizers on Acinetobacter baumannii were studied. These Gram negative bacteria have recently been implicated in various infections, mainly acquired in hospitals. They have outstanding characteristics of multidrug high resistance to antimicrobial agents. The best photodynamic effect was obtained when A. baumannii cultures were treated with light activated deuteroporphyrin (Dp) at a concentration of 34 mumoles l-off and polymyxin nonapeptide (PMNP) at a concentration of 200 mumoles l-1. At these concentrations the culture in brain heart infusion (BHI) broth was found to be sterile after l h of treatment. Some inhibition was also obtained under the same conditions with Cd-texaphyrin (Cd-Tx) in the presence of PMNP. Treatment with various other photosensitizers in the presence of PMNP exhibited only marginal antibacterial activity. The cationic photosensitizer tetra-methylpyridyl porphine (TMPyP) did not exhibit any photodynamic effect on A. baumannii when illuminated during its growth in BHI broth. Bacteria grown in nutrient broth or suspended in saline and treated by TMPyP resulted in a significant photoinactivation by the sensitizer alone even in the absence of PMNP. It was found that a high concentration of the proteins present in BHI or in serum prevent TMPyP from acting as a photosensitizer against A. baumannii. Bovine serum albumin at the same high protein concentration prevents Dp (in the presence of PMNP) to act as a photosensitizer. The anionic photosensitizer tetra-sulfonatophenyl porphine (TPPS4) did not show any photodynamic effect in high or low protein media. In this study it was found that despite the high resistance of the Acinetobacter baumannii to antibiotics, these bacteria can be significantly photoinactivated by treatment with either Dp + PMNP or TMPyP in low protein content environments. When the protein concentration is high photoinactivation efficiency depends on the type of protein present in the medium.

Acinetobacter baumannii colonization in ventilated preterm infants

The role of Acinetobacter baumannii in infections in ventilated preterm infants was evaluated in 15 colonized infants (11 male, 4 female) in a pediatric intensive care unit. These cases were randomly matched by birth weight and gestational age with ventilated non-colonized controls (8 male, 7 female). Case records were reviewed for signs and symptoms of infection. Colonized infants were ventilated significantly longer (p < 0.05) than controls, and had body temperatures of > 37 degrees C for a significantly longer period of time (p < 0.05). No other parameter of infection differed significantly between the groups. The duration of intensive care treatment did not differ between cases and controls, nor did the weight gain during intensive care treatment. No fatalities occurred in either group.

Survival of Acinetobacter baumannii on dry surfaces

Acinetobacter spp. have frequently been reported to be the causative agents of hospital outbreaks. The circumstances of some outbreaks demonstrated the long survival of Acinetobacter in a dry, inanimate environment. In laboratory experiments, we compared the abilities of five Acinetobacter baumannii strains, three Acinetobacter sp. strains from the American Type Culture Collection (ATCC), one Escherichia coli ATCC strain, and one Enterococcus faecium ATCC strain to survive under dry conditions. Bacterial solutions of the 10 strains were inoculated onto four different material samples (ceramic, polyvinyl chloride, rubber, and stainless steel) and stored under defined conditions. We investigated the bacterial counts of the material samples immediately after inoculation, after drying, and after 4 h, 1 day, and 1, 2, 4, 8, and 16 weeks of storage. A statistical model was used to distribute the 40 resulting curves among four types of survival curves. The type of survival curve was significantly associated with the bacterial strain but not with the material. The ability of the A. baumannii strains to survive under dry conditions varied greatly and correlated well with the source of the strain. Strains isolated from dry sources survived better than those isolated from wet sources. An outbreak strain that had caused hospital-acquired respiratory tract infections survived better than the strains from wet sources, but not as well as strains from dry sources. Resistance to dry conditions may promote the transmissibility of a strain, but it is not sufficient to make a strain an epidemic one. However, in the case of an outbreak, sources of Acinetobacter must be expected in the dry environment.

The increasing significance of outbreaks of Acinetobacter spp.: the need for control and new agents

Acinetobacter spp. are Gram-negative non-fermentative bacteria which may be isolated as commensals from human skin, throat and intestine but are also increasingly responsible for hospital infections. Owing to frequent changes in their taxonomy, their pathogenic role in humans has not been clear but today acinetobacter is considered to be a significant nosocomial pathogen in outbreaks of hospital infections predominantly in intensive care units. Nosocomial infections due to acinetobacter include urinary tract infections, bacteraemia, wound and burn infections, but also they are frequently isolated from ventilator-associated nosocomial pneumonia. The frequency of hospital outbreaks of acinetobacter infections has required the development of reliable typing methods. As well as conventional 'phenotypic' methods (serology, biotyping, phage typing), 'genotypic' systems (ribotyping, plasmid profiles, pulsed-field gel electrophoresis) have been utilized for strain identification. These typing systems should allow a better understanding of the epidemiology of acinetobacter in the hospital environment, e.g. sources, modes of transmission, and result in more efficient preventive measures. Acinetobacter infections are difficult to treat owing to their frequent multiple resistance to the antibiotics currently available for the treatment of nosocomial infections; various mechanisms of resistance to beta-lactams and amino-glycosides have been identified in the genus. Combination therapy is usually recommended for treatment of acinetobacter nosocomial infections and active antibacterials include imipenem, ceftazidime, amikacin and the newer fluoroquinolones. Careful in vitro testing of the activity of combinations of these drugs is recommended prior to their use.

Clinical and epidemiological investigations of Acinetobacter genomospecies 3 in a neonatal intensive care unit

A prospective study of Acinetobacter isolates from a neonatal intensive care unit was performed for 24 months. Fifty-six isolates were obtained from 21 patients, and another eight were obtained from environmental specimens. Infection due to Acinetobacter organisms was established for 16 patients, 6 with septicemia, 9 with pneumonia, and 1 with a wound infection. Further investigations were performed with 38 representative isolates. Twenty-nine isolates were identified as unnamed DNA-DNA hybridization group (genomospecies) 3, three were identified as genomospecies 2 (Acinetobacter baumannii), one was identified as genomospecies 5 (Acinetobacter junii), three were identified as genomospecies 14, and two were unclassified. Eight distinguishable protein profiles, coded I through VIII, were found by cell envelope protein electrophoresis. Profile V, a common profile, was observed for 17 isolates that had been recovered from 11 patients and 1 dust specimen. These isolates, all of which belonged to genomospecies 3, had similar antibiograms and biotypes. This study has revealed that genomospecies 3 can be associated with infection and be spread in hospitals.

Acinetobacter spp., saprophytic organisms of increasing pathogenic importance

Acinetobacter spp. are Gram-negative non-fermentative bacteria commonly present in soil and water as free-living saprophytes; they are isolated as commensals from skin, throat and various secretions of healthy people. There have been frequent changes in their taxonomy so that their pathogenic role in humans has been understood only recently: Acinetobacter has emerged as an important nosocomial pathogen involved in outbreaks of hospital infections. This ubiquitous organism can be recovered from the hospital environment, from colonized or infected patients or from staff (hand carriage). Acinetobacter as an opportunistic pathogen is involved in nosocomial urinary tract infections, bacteremia, wound and burn infections. Its predominant role is observed in nosocomial pneumonia, particularly in fan-associated pneumonia. Acinetobacters are responsible for difficult-to-treat infections due to their frequent multiple resistance to major antibiotics available for the treatment of nosocomial infections. Various mechanisms of resistance to beta-lactams and aminoglycosides have been recognized in these bacteria. Combination therapy is usually recommended for the treatment of nosocomial infections. The increasing pathogenic importance of Acinetobacter spp. and the increasing frequency of hospital outbreaks of acinetobacter infections has made the development of reliable typing methods imperative. Beside conventional "phenotypic" methods (serology, phage typing), genotypic systems (ribotyping, plasmid profiles, pulse-field gel electrophoresis) are currently advancing.

Comparative characterization of Acinetobacter strains isolated from different foods and clinical sources

Eighty-three Acinetobacter strains from clinical sources, and 170 from various foods (including fresh and spoiled meat and fish, vegetables, raw milk and cheese) were identified according to recently improved taxonomy, using a computer-assisted probabilistic method based on phenotyping tests. Apart from some atypical characters, most of the strains (94%) were identified to belong to the genospecies or groups of genospecies described in the literature. Among our strains from hospitals, the A. calcoaceticus- A. baumannii complex predominated, whereas the strains isolated from food were predominated by genospecies 7 (A. johnsonii), followed by genospecies 8/9 (A. lwoffii). The isolates from clinical environments showed a major incidence of antibiotic resistance, haemolytic strains and strains producing polysaccharidic material.

In vitro antimicrobial production of beta-lactamases, aminoglycoside-modifying enzymes, and chloramphenicol acetyltransferase by and susceptibility of clinical isolates of Acinetobacter baumannii

Antimicrobial susceptibility testing was performed on 54 epidemiologically unrelated clinical isolates of Acinetobacter baumannii by using a standard agar dilution technique. On the basis of the in vitro activities, imipenem and doxycycline were the most active agents, whereas amikacin, isepamicin, and the new fluorquinolones ciprofloxacin and ofloxacin presented moderate activity. Cephalosporinase activity was found in 98% of the strains, whereas lactamases of TEM type 1 and one with a pI of 7 to 7.5 were present in 16 and 11% of the strains, respectively. Resistance to aminoglycosides was explained by the production of the three classes of aminoglycoside-modifying enzymes, with predominance of aminoglycoside-3'-phosphotransferase VI in 28% of the strains.

Serotyping of clinical isolates of Acinetobacter baumannii and genospecies 3: detection of additional serovars

Continued serological monitoring of clinical isolates of Acinetobacter baumannii and genospecies 3 permitted identification of 7 new serovars of A. baumannii and 8 additional serovars of genospecies 3.